Fixed gear chainline

[Jai Ma]

I've set up the cranks and bottom bracket that I'm going to use for my fixed
gear project (Thanks to Sheldon Brown for his excellent articles). The
chainring chainline measures 43.5 mm. So with my 124 mm dropout spacing (Is
that probable? It was a six speed. I've measured it over and over) I
calculate the cog should be 18.5 mm from the bolt that goes against the
inner side of the dropout. So far so good, I respaced the hub along the
axle to that and visually it looks perfect.

I have two issues. After I redish the wheel I will end up with a slight
negative dish. Aside from the fact that I think I will have to switch the
spokes from left to right, it doesn't seem like a problem to me, but I have
no experience and wonder if this seems reasonable?

The other issue is that in the future I would like to put a flip/flop hub on
it. It seems to me that would mean I will be forced to make the crank and
bb chainline conform to the hub instead of the other way around as I'm
doing. Could I get a flip/flop hub to have the right rear chainline on a
bike with 124 mm dropout spacing and a 43.5 mm chainline up front?

 

[John Dacey]

"Non si male nunc et olim sic erit." - Quintus Horatius Flaccus
On Tue, 7 Sep 2004 17:18:39 -0700, "Jai Ma" wrote:

<snip>

>I have two issues. After I redish the wheel I will end up with a slight
>negative dish. Aside from the fact that I think I will have to switch the
>spokes from left to right, it doesn't seem like a problem to me, but I have
>no experience and wonder if this seems reasonable?

Don't move the spokes from their current orientation in the hubshell.
If the length(s) aren't appropriate to redish the wheel with the ones
fitted now, either rebuild it with new spokes or (better yet)
accelerate you plans to acquire the new wheel that you mention below.

>The other issue is that in the future I would like to put a flip/flop hub on
>it. It seems to me that would mean I will be forced to make the crank and
>bb chainline conform to the hub instead of the other way around as I'm
>doing. Could I get a flip/flop hub to have the right rear chainline on a
>bike with 124 mm dropout spacing and a 43.5 mm chainline up front?

Assuming the chainline calculations you made (in the section I
snipped) for your crank are accurate, you should be able to simply fit
a 1.5 mm spacer (plus or minus a smidgeon, depending on the exact
components used) between the sprockets and the sprocket seats on the
shell of most track hubs that conform to the common track chainline
standard. Many track hubs spaced by default at 120 mm will allow you
to add a 2 mm spacer between each cone and locknut to symmetrically
space the hub to 124 OLN.

There's some chainline info for track equipment at
http://www.businesscycles.com/tr-refspec.htm#chainline


-------------------------------
John Dacey
Business Cycles, Miami, Florida
http://www.businesscycles.com
Since 1983
Our catalog of track equipment: online since 1996
-------------------------------